Discharge tube for electron multiplication



Nov.25, 1941. R. FORBERGER I 2,263,725

DISCHARGE TUBE FOR ELECTRON MULTIPLICATION Filed Sept. 22, 1958 INVENTOR. ROBERT FORBERGER BY A TTORNEY.

Patented Nov. 25, 1941 DISCHARGE TUBE FOR ELECTRON MULTIPLICATION Robert Forberger, Berlin, Germany, assignor to Tielefunken Gesellschaft fiir Drahtlose Telegraphic m. b. H., Berlin, Germany, a corporation of Germany Application September 22, 1938, Serial No. 231,132 In Germany September 27, 1937 6 Claims.

The invention relates to a device adapted to produce oscillations, especially of ultra-high frequency, by the aid of a series or cascaded multiplier. According to prior practice recourse has been had in series multipliers for oscillation generation either to regeneration of a stage to a preceding stage or else the negative characteristic of the secondary-electron emitting electrode has been utilized.

For the purpose of generating oscillations, the present invention is predicated upon other means and ways. According to the invention part of the electrons in a stage of the series multiplier is branched off directly or by influence action and fed to a grid mounted in the electronic stream of a preceding stage. The invention distinguishes itself from the methods known in the art in that anauxiliary electrode is provided which does not partake of the multiplication process. This auxiliary electrode and its leads to the grid of the preceding stage may, therefore, be designed quite independently of the other electrodes and be adapted to the particular requirements of wave generation where extremely high frequencies are dealt with. In other words, shorter waves may thus be generated than by other methods known in the art.

My invention will now be described in more detail, reference being made to the accompanying drawing in which Figure 1 illustrates an electron discharge tube having electrodes suitably formed and arranged for carrying out the invention, and

Fig. 2 shows another electron discharge tube having its electrodes somewhat differently arranged.

Referring to Fig, 1, I show an incandescible cathode I, a control grid 2, and denote target electrodes 3, 4, 5, 6 and I. These target electrodes form a cascade multiplier by virtue of the fact that, in operation, they are maintained at progressively higher and higher positiv potentials with respect to the cathode potential. The electrons travel along the lines indicated by the arrows. The width of the beams as shown is merely a conventional indication of the gradual increase in the number of the electrons. In the embodiment of Fig. 1 the electron beam passing from the electrode 5 to the electrode 6 is surrounded by an annular auxiliary electrode 8. The electrons passing through the same induce positive charges upon the electrode 8, while a corresponding negative charge by way of a connecting lead is imparted to the control grid 2.

In other words, the grid becomes more negative and it cuts oiI the flow of electrons in the ex-. treme case. As a result the influence action on the electrode 8 ceases, the charges become equalized, and the grid as a consequence becomes positive. The electrons again are ableto flow through this grid, and the cycle is repeated.

Referring to the embodiment of Fig. 2, one of the target electrodes, say, electrode 4 has an opening or is of reticulated or screen mesh formation. Through this opening fiy electrons and impact upon an auxiliary electrode 5'. The secondary electrons here liberated may be urther multiplied so as to insure additional gain. However, it will also suffice to provide but a single stage and to collect or gather the amplified electronic currents with the aid of an electrode 6'. This electrode is united with a grid-shaped electrode 20. mounted directly behind the control grid 2. This grid 2a normally is positively biased to such a high value that together with the negatively biased control grid there results a suitable control potential. As a result of the electron impact, electrode 6' becomes more negative, and this may be further promoted, if desired, by inserting a suitable resistance in the lead. But, thus, also the electrode 2a becomes more negative and the aggregate potential decreases so markedly that the electron current is intercepted. Thereupon the cycle is repeated as hereinbeiore described.

In the leads between the electrode 8 and the grid 2 in Fig. 1, or between electrode 6' and the grid 20!. in Fig. 2, inductances or capacities may be inserted by the aid of which the frequency of the oscillations may be varied.

In the presence of given dimensions, the frequency of the oscillation may be varied within certain limits by alteration of the applied potentials.

It will be understood that oscillations of different wave shapes may be generated in either of the tubes illustrated in Figs. 1 and 2. This can be accomplished by suitable design of the target electrodes, and also by adjustment of the dis-.

tances between these electrodes or the fixing of suitable potential gradients as applied to the electrodes, thus controlling the electron transit times. By varying the shape of the auxiliary electrode 8 or 5, or the relation of the electron transit times in the progressive stages, still other advantageous results can be produced.

I claim:

1. An electron discharge tube having a cathode, a control grid, means including a series of anodal targets for obtaining secondary emission in successive stages, electrode means positioned in the path of the electron stream in one of said stages, and means in said tube connecting said control grid with said electrode.

2. An electron discharge tube in accordance with claim 1' wherein said electrode means is a tubular electrode, and the last said means is constituted by a metallic connection between said tubular electrode and said control grid.

3. An electron discharge tube in accordance with claim 1 and having an electron multiplier stage interposed between said electrode means and said control grid.

4. An electron discharge tube in accordance with claim 1 and having one of said anodal targets perforated, whereby a portion of the electron stream directed toward that target is shot through said target, and a secondary electron emissive element positioned angularly with re spect to said target and said electrode means for controlling the potential of said control grid.

5. An ultra-high frequency oscillator tube system comprising a plurality of target electrodes adapted to function as cascaded electron multiplier stages, means for diverting a portion of the electron stream in one of said stages, a control grid positioned in the path of electrons of a stage preceding said one of said stages, and means for making electrical connections to both said means and said grid.

6. A secondary electron emissive tube comprising, a plurality of electron multiplier stages, a source of primary electrons, means between two of said stages for inducing a potential in proportion to the number of electrons flowing between said two stages, and means in the path of said primary electrons coupled to said inducing means for interrupting primary electrons from the source by the induced potential.

ROBERT FORBERGER. 

